Nocera thinks what happened to Madoff's investors was horrible, but he also points out that the first rule of personal finance is diversification. He wrote:

People lose it all because they start a company that turns out to be misguided, or because they do something that is risky, hoping to hit the jackpot. Taxpayers don’t bail them out, and they shouldn’t start now. Did the SEC foul up? You bet. But that doesn’t mean the investors themselves are off the hook. Investors blaming the SEC for their decision to give every last penny to Bernie Madoff is like a child blaming his mother for letting him start a fight while she wasn’t looking.

Removing Madoff from the equation, do you think some victims acted negligently by putting all their money in one place, or does most of the blame lie with the SEC?

Never ever put all your eggs in one basket. There is a reason the saying "If it's too good to be true, then it probably isn't" is so popular.
From the begining I kept wondering to myself, how could anyone put their whole life saving into the hands of one person?

I don't know why you would give anyone your entire life savings. There does not need to be a government agency to tell you that handing over all your money is a bad idea. What if you don't get it back? Do you really need someone to tell you this is a bad idea?

exactly...how did you think the returns he was promising were real? it's like every other "too good to be true" deal out there - anyone who wasn't suspicious was an idiot and everyone else had their heads in the sand...and, to think, he's 70...a few more years and he could have gotten away with it completely!

The SEC failed to do their job, but the investors are to blame too, because they quite obviously left their brains at Madoff's coat check when they invested with him.
Everyone who knows a little about how businesses are run, should know the kinds of returns he promised were fanciful.

I really don't get what the the Bernie Madoff story is such a big deal. He conned a bunch of rich people out of money and then squandered it.
Every day, the federal government takes our money and squanders it.

The investors did make serious mistakes, but the SEC is staffed with alleged experts who are paid to find people and problems like Madoff and his scam. A lot of people invested their money with one person who passed it on to Madoff. Either way, Madoff's investors are paying for their mistake.
The SEC meanwhile is staffed with alleged experts who are paid to ferret out people and problems like Madoff and his scam. People who aren't up to the job they were hired to do should be relieved of that job.